Massive stars are responsible for energetic feedback effects that drive evolutionary processes in star-forming galaxies. Radiative feedback is especially important because it is thought to be responsible for cosmic reionization, as well as ionization of the diffuse, warm ionized medium. Mechanical and chemical feedback are also fundamental in driving galactic chemical evolution, star formation, and other major evolutionary processes. I first describe parameterization of massive stars as a population, to then quantify feedback effects in terms of simple, analytic relations. This review then focuses on our current understanding of radiative feedback as studied in the local universe.